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许多观测表明:相对小的应力变化就能触发或制止地震。这个结果令人惊奇,因为触发地震的应力扰动只是引发地震应力降的一小部分。我们用符合物理实际的数值模型模拟地震断层来研究这个现象。断层是不均匀的,因此,断层表面各处会有不同的破裂判据。我们将不均匀断层模拟成由许多小区域组成,大部分小区域是均匀的,在小区域上可发生简单的库仑破裂。因为那些小区域会多次(重复)破裂,断层上的存储应力会很不均匀。我们看到围限应力十分之几巴的小变化有可能引起大地震提前或延迟几十年发生。因为这样的应力变化可以由附近的地震产生,也可以在较长时间尺度内由远处的大地震的震后应变扩散产生,所以,为了可靠地估计地震发生的概率,必须考虑这些应力扰动。
Many observations show that relatively small stress changes can trigger or stop earthquakes. This result is surprising because the stress disturbance that triggered the earthquake was only a small part of the seismic stress drop. We study this phenomenon by simulating seismic faults in a physical numerical model. Faults are not uniform, so there will be different criteria for fracture throughout the fault surface. We model the inhomogeneous faults as being composed of many small regions, most of which are uniform and where simple Coulomb failure can occur in small regions. Because these small areas will be repeated (repeated) rupture, the storage stress on the fault will be very uneven. We see that a small change of a few tenths a percent of the confining stress is likely to cause a large earthquake to occur ahead of schedule or for several decades. Because such stress changes can be produced by nearby earthquakes or by post-earthquake strain-induced dispersion of distant earthquakes over longer time scales, these stress disturbances must be considered in order to reliably estimate the probability of earthquakes.